/*
 * [New BSD License]
 * Copyright (c) 2011-2012, Brackit Project Team <info@brackit.org>  
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Brackit Project Team nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.brackit.xquery.node.parser;

import org.brackit.xquery.atomic.Atomic;
import org.brackit.xquery.atomic.QNm;
import org.brackit.xquery.node.stream.ArrayStream;
import org.brackit.xquery.node.stream.AtomStream;
import org.brackit.xquery.xdm.DocumentException;
import org.brackit.xquery.xdm.Stream;

/**
 * A parser that announces each top level element from the input parsers as a
 * new document.
 * 
 * @author Martin Hiller
 * 
 */
public class CollectionParser implements SubtreeParser {

	private final Stream<SubtreeParser> parsers;

	public CollectionParser(Stream<SubtreeParser> parsers) {
		this.parsers = parsers;
	}
	
	public CollectionParser(SubtreeParser parser) {
		this.parsers = new AtomStream<SubtreeParser>(parser);
	}
	
	public CollectionParser(SubtreeParser[] parsers) {
		this.parsers = new ArrayStream<SubtreeParser>(parsers);
	}

	@Override
	public void parse(SubtreeHandler handler) throws DocumentException {

		CollectionHandler collHandler = new CollectionHandler(handler);

		// announce begin / begin fragment
		handler.begin();
		SubtreeParser current = null;
		while ((current = parsers.next()) != null) {
			current.parse(collHandler);
		}
		parsers.close();
		handler.end();
	}

	/**
	 * Handler class used by the CollectionParser.
	 */
	private class CollectionHandler implements SubtreeHandler {

		private final SubtreeHandler handler;

		private int level;

		public CollectionHandler(SubtreeHandler handler) {
			this.handler = handler;
			this.level = 0;
		}

		@Override
		public void attribute(QNm name, Atomic value) throws DocumentException {

			if (level == 0) {
				// attribute on top level => invalid state
				throw new DocumentException("Attribute on top level!");
			}

			handler.attribute(name, value);
		}

		@Override
		public void begin() throws DocumentException {
			// do not propagate local begins
		}

		@Override
		public void beginFragment() throws DocumentException {
			handler.beginFragment();
		}

		@Override
		public void comment(Atomic content) throws DocumentException {

			if (level == 0) {
				// comment on top level => invalid state
				throw new DocumentException("Comment on top level!");
			}

			handler.comment(content);
		}

		@Override
		public void end() throws DocumentException {
			// do not propagate local ends
		}

		@Override
		public void endDocument() throws DocumentException {
			handler.endDocument();
		}

		@Override
		public void endElement(QNm name) throws DocumentException {

			handler.endElement(name);
			level--;

			if (level == 0) {
				// top level element => document ends
				handler.endDocument();
			}
		}

		@Override
		public void endFragment() throws DocumentException {
			handler.endFragment();
		}

		@Override
		public void endMapping(String prefix) throws DocumentException {
			handler.endMapping(prefix);
		}

		@Override
		public void fail() throws DocumentException {
			handler.fail();
		}

		@Override
		public void processingInstruction(QNm target, Atomic content)
				throws DocumentException {

			if (level == 0) {
				// processing instruction on top level => invalid state
				throw new DocumentException(
						"Processing instruction on top level!");
			}

			handler.processingInstruction(target, content);
		}

		@Override
		public void startDocument() throws DocumentException {
			// do not propagate local document boundaries
			handler.startDocument();
		}

		@Override
		public void startElement(QNm name) throws DocumentException {

			if (level == 0) {
				// top level element => announce as new document
				handler.startDocument();
			}

			level++;
			handler.startElement(name);
		}

		@Override
		public void startMapping(String prefix, String uri)
				throws DocumentException {
			handler.startMapping(prefix, uri);
		}

		@Override
		public void text(Atomic content) throws DocumentException {

			if (level == 0) {
				// text on top level => invalid state
				throw new DocumentException("Text on top level!");
			}

			handler.text(content);
		}
	}
}
